I love roleplaying games, and I’ve DM (or GMed) them on and off since I was 8 years old strong-arming my little brother into playing D&D with me since we didn’t have any friends within walking distance of our house. Being the greatest Dungeon Master in the world has always been one of my not-to-secret goals (isn’t it everyone’s?), although hearing about other games and other DMs I know I’ve got lots of room for improvement; there’s lots of skills that make a good DM, and no one shoe fits all since every group of players is different.

But what are some common (and not-so-common) mistakes of DMing? What are some errors to avoid? Here’s some bad ideas I’ve discovered over my years of DMing, by making all these mistakes myself. I screwed up all these different ways so you don’t have to. Look upon my DMing works, ye mighty, and despair!

1. Don’t make hasty decisions. And if you do make hasty decisions, don’t be afraid to undo them. DMing is all about making decisions on the fly (though preparation helps too). I can’t count how many times I regretted some in-the-moment decision and felt l’esprit d’escalier d’RPG (sorry, I don’t actually know French) thinking about it later. It’s great to be quick-witted, but it’s also perfectly fine to call a time-out to think about the implications of some player action and how to respond to them. Or just apologize and undo what you said before: in one horror game, the characters opened fire on a mutated insect-man and killed him according to the dice, but I wanted insect-man to survive so I blurted out “His dog jumps in the way and takes the bullets!” Everyone booed and complained, so I backed down: “Okay…okay…that doesn’t happen. The dog doesn’t block the bullets, it just whines over the dying body of its master.” Not one of the highlights of my DMing career, but stubbornly sticking to such a silly decision would have been even worse, and even more annoying to the players.

2. Know the rules. At least enough to make interesting fights and challenges. Some RPGers prefer rules-light games, others enjoy tinkering and rules-lawyering. Whichever type a group prefers, in order to make things exciting, the DM should have some idea of what challenge is appropriate and what chance the player-characters have of making dice roll X or beating enemy Y. This might mean knowing dice percentages well enough so that you aren’t surprised when the players make some roll you thought was impossibly hard, or befuddled that the players can’t make some roll you thought was easy. (In either case, the most important thing is to have a meaningfully different branching path prepared whether the players succeed or fail.) In D&D, this often means adjusting the power levels of enemies on the fly to get that delicate balance, different for each group, of a fight that seems nail-biting and intense but not unfair and hopeless.

Making things too easy can suck too; when I DMed a college Shadowrun game I wanted ‘movie-like’ climactic fight scenes where the players all worked together to fight one big villain. However, according to the Shadowrun rules there are only 10 Wound Levels, and any given attack that a player puts all their power into has a pretty good chance of dealing 6-10 Wound Levels and crippling or killing an enemy outright. Basically, the Shadowrun system is best suited to tactical-squad combats with lots of combatants running around on both sides, but I was so in love with the Big Boss idea I didn’t take advantage of this, and game after game ended with the players saving up all their Karma Dice for that One Big Roll where they blasted my should-have-been-awesome solo enemy to pieces. Although players are rarely unhappy when they blast an enemy to pieces, the results were always anticlimactic, and I repeated this mistake so often one of the players eventually pointed out what I was doing wrong.

3. Don’t let one player dominate the game. In the ’80s and ’90s before all the trolls moved to online gaming, obnoxious dudes would show how badass they were by showing up at D&D games with ridiculously overpowered characters. In level-based games like D&D it’s actually fairly easy to police this by making sure everyone is the same level and doesn’t show up laden with magic artifacts or ‘my daddy is the king of the world’ backstories, but this sort of thing is possibly even more troublesome in poorly-balanced point-based games where 6 Skill Points are 6 Skill Points whether they’re spent on Cooking or Heavy Machine Gun. It’s the DM’s responsibility to make the cook and the machine gunner equally valuable!

One problem is the person who shows up with an incredibly powerful character ‘from their old campaign,’ like the guy who joined our college Shadowrun game with an insanely powerful, absurdly rich elven assassin. I failed as a DM by not looking at his character sheet too closely, and soon he was annoying the other players with his seemingly infinite resources of wealth and his sly ‘I’m so much powerful than you all’ insinuations. Eventually, after one particularly obnoxious exchange, one player-character started an “everybody against that one guy” fight and killed him (it was a close fight; he really WAS overpowered). Since the other players started the violence, were they in the wrong…? No, *I* was in the wrong as DM for letting him play such a ridiculous character. And since Shadowrun Guy was just being arrogant, not aggressive, this isn’t wasn’t even as bad as people who are *really* bullies and who go into games out-shouting and intimidating other players: in some cases, the DM really has to lay the smackdown, like in one game I played in which ended with the jerk leaving the game and everyone else at the table burning his character sheet with a Bic lighter. Basically, a DM has to be like a scout leader and smooth over conflicts between the players.

4. Make every game count! Don’t waste the players’ time or yours. I was once running a game set in Ancient Egypt in which everything took much too much time. Distances between locations were too long; traveling from Memphis to Luxor, a few hours’ journey by train today, took weeks of game time. I wanted to impress the players with a sense of distance and scale and to make them face lots of random encounters, but the players found this merely boring. Furthermore, the plot threads that I’d tried to plant in Memphis were forgotten when they arrived in Luxor, four to five real-life game sessions later, and the players responded to my aimless, drifting campaign by drifting…and drifting…until we’d all lost the plot together with all sense of urgency. In retrospect, I should have just said “You travel for a week, occasionally fighting wolves and bandits. Then you arrive in Luxor. BAM. Then here’s what happens…” Whether your game is sandboxy or linear, don’t save your ‘good ideas’ for later; use them NOW, and then come up with NEW good ideas. This ties into Tip 4.5: when things are getting too slow in-game, have some monsters show up or some crazy event happen, fast!

5. Don’t kill people’s characters when they’re not there. Perhaps this seems obvious, but it’s hard to deal with characters when the players don’t show up. The best option is probably to have the absent characters become uncharacteristically quiet and fade into the background, but occasionally, especially in fighting-heavy RPGs, the other players want to play the absent character for extra firepower. In one D&D game one of these ‘remote-controlled’ characters jumped into the front lines in an attack on an evil temple. I decided to roll the enemy’s attack out in the open…I rolled a 20…and then rolled maximum damage. Instead of fudging the rules and saying “She’s just knocked unconscious,” (see Rule #1), I idiotically ruled that the character’s head was lopped off. I still play with the player whose character I killed, and he still gives me grief about it. (Who can blame him?)

6. Have some idea of what kind of game players expect, and give them what they want. DMs have the same dilemma as all creators: balancing the niche, weird, player-killing things they want to run with what their players want to play. In college, around the time “Vampire: The Masquerade” was becoming popular, a dorm neighbor who’d never played RPGs before approached me and said she’d heard about “Vampire” and wanted to try it out. Excited to ‘convert’ a new roleplayer, I invited her and some other semi-gamey friends to a Vampire one-shot. Unfortunately, instead of crafting a scenario involving the types of urban-fantasy, Anne-Ricey things that would draw someone to Vampire — vampiric angst, sinister conspiracies, beauty & decadence, superheroic ability beyond mere mortals — or better yet asking her why she was into Vampire!! — I came up with a Lovecrafty scenario involving fighting evil vampires whose true forms were a writhing mass of maggots. I let my love of slimy monsters overcome the type of scenario that I knew deep down would appeal to a new Vampire player, and it was clear that the new players found the resulting one-off more confusing and gross than exciting. My dorm mates never played RPGs with us again.

7. Don’t let one player be out of the action for a long time while other players are doing stuff. In roleplaying games, unless there’s a spare DM to talk to the other person, splitting the party sucks. In a Call of Cthulhu game I ran once, three of the player-characters went to a closed storefront for what they thought would be a short investigation while the fourth character decided to stay back at the hotel. The three investigators found themselves in the hidden sub-basement of the store, fighting hordes of cultists, where they stayed for three hours of real-life time; the other player decided “I’m going to go to the store after all and see what they’re up to!” but since we’d already established the store was half an hour’s drive from the hotel and the fight only took a few minutes of game time I, in the name of ‘realism’, idiotically didn’t let him arrive until after the fight was over. The player left the game soon after that.

8. Be flexible; be open to game-changing crazy player ideas. ESPECIALLY if they roll well. I was running a convention D&D one-shot in which the players were heroes trying to save a city under siege by lizard men (a situation inspired by the Crusaders’ siege of Jerusalem). Searching the catacombs under the city for a holy weapon that could turn the tide, the players encountered the evil liches of the city’s religious patriarchs. One player announced “I’m going to convince them that I am the messiah they’re waiting for and they should serve me!” I let him roll a long-shot Diplomacy roll. He rolled a 20. But, I’d already decided in my mind that the PCs would have to fight the liches, so I dismissed his idea and had the liches brush it off, even though in retrospect it OBVIOUSLY would have been the awesomest possible way to develop the story. The player left the game soon after that.

9. Make sure players don’t feel targeted racially, sexually, sexual-orientation-wise, etc. This of course applies to every social interaction, not just RPGs. But in RPGs (1) you gotta have conflict which involves portraying jerks, (2) people are by definition playing characters ‘out of their skin’, of different ethnicities, genders, etc. and (3) the tropes of popular RPG genres are frequently derived from to-varying-degrees-racist writers like H.P. Lovecraft, Robert E. Howard, J.R.R. Tolkien, etc. In this case I’ll pick an example where I was player, not DM; the best D&D campaign I’ve ever played in was an “Oriental Adventures” campaign run by an Asian-American DM and played by mostly white players. Many of the white players had ‘Asian’ characters, including myself, and the DM encouraged this…naturally! It’s role-playing! All was well until another player decided to create a Chaotic Neutral wizard and I drew a sketch of his character for him, using the ‘evil Oriental wizard’ tropes: long pencil mustache, long fingernails, shaved head, flamboyant robes, etc. Upon seeing the drawing, our DM asked “What the hell is that??” Having not intended to offend, I apologized and redrew the character to make him less Fu Manchu-like, but the damage was done. Among many other reasons, I can attest he was a truly great, truly fair DM because my character didn’t die horribly soon afterward.

10. Don’t physically hit the players. Once, years ago, I read an article on “running horror RPGs” which contained the advice “In a horror game, try to frighten the players! When you’re playing bad guys, intimidate them! Even take a fake swing at them!” The first two sentences are great, but once, while running a Kult game in which the players were dealing with an evil homicidal car-junkie ‘transporter’ (think Vin Diesel in The Fast & The Furious crossed with the Richard Matheson story/movie Duel), I tried the third. I miscalculated my swing and struck one of my friends in the head. I profusely apologized and, because he is a saint, my friend forgave me. We still play D&D regularly. Don’t count on having such awesome friends as I do and DON’T HIT YOUR PLAYERS. Ahh, memories!